UPDATE: Forest Avenue in Portland is now open to all traffic.

Fire officials said they are still on the scene investigating the cause of the fire.

PORTLAND, Maine (NEWS CENTER) — Crews are working to extinguish a structure fire on Forest Avenue in Portland.

It broke out at 732 Forest Avenue near Sun Tan City.

Portland Fire Chief David Jackson said, to his knowledge, all occupants made it out safely, including some pets.

The chief said that when firefighters arrived they found the back of the building consumed by heavy fire.

The Red Cross was called in to assist with relief efforts, and residents were not allowed back inside as of early Tuesday morning.

A portion of Forest Avenue was closed at Ocean Avenue.

At least five fire trucks and about two dozen firefighters were on scene.

The cause is still unknown.

More details to follow.